| Coal is the main energy resource in China. Clean and effective utilization of coal issignificant to reduce coal-combusting-pollution and to save coal energy. In terms of theprocess of coal combustion, the distribution of minerals in the coal and the burningcharacteristics of coal, etc. the progress in the mutual relations of the particle size, thedistribution of minerals, the burning characteristics of pulverized coal at home and abroad arereviewed. Because the main utilization method of coal is combustion, the distribution andinfluence of minerals in the pulverized coal from the industrial pulverizing process are studied.The distribution of minerals in the pulverized coal chaning with the size and its influence onthe characteristic of combustion are analyzed, which are in order to provide basic data for theindustrial application of particle size grading combustion of pulverized coal in the new dryprocess cement plant. All of above have provided theoretic guidance for the effectiveutilization to the poor quality coal, strengthening the combustion of pulverized coal. It is alsosignificant for the efficient and clean utilization of coal in the Coal-fired power plant.The research on the industrial single pulverized coal shows that the samples ofpulverized coal from the Tong Li Cement Plant in Xixiang Henan (HN), Xicheng CementPlant in Shanxi (SX) and China Cement Plant in Nanjing Jiangsu (JS) are different rankbituminous. The ash of three pulverized coal sample are increasing with the increase ofdensity fraction and decreasing with the increase of the particle size. The yield distribution ofcoal sample is like a dumbbell which means the separation degree of minerals and organics ishigh. Minerals in the SX coal sample existed in the form of the external mineralindependently.Based on the results of the float and sink test and the laser particle size analysis, thecalculation formula of ash, volatile and the yeild of each size friction in the pulverized coalwere obtained by the deduction of the mathematic calculation process. The establishment ofthe mathematical model provides the theoretical support to the research on the distribution ofthe composition of the pulverized coal.Research on the mixed pulverized coal from the industrial field showed that the mixedpulverized coal samples collected from Guangxi Hua Hong Cement Co., Ltd.(HH),GuangxiCR Cement Co., Ltd.(HR),Jiangxi Evergreen Cement Co., Ltd.(WNQ),Shanxi WittonCement Co., Ltd.(WD)and Anhui Conch (Di Kong) Cement Co., Ltd.(DG) indicated a lawthat the ash decreases with the increase of the particle size. By determining the appropriate classification size of particles, high-quality and low ash pulverized coal can be obtained afterthe classification after using the classification method. Samples of the pulverized coal showthe trend that the yield of high density coal sample decreases with the increasing particlesize,which shows that the content of external mineral decrease with the increasing particlesize and the change of the ash with the particle size is lead by the high density fraction.The influence of the grinding process and coal blending on mineral distribution wasresearched, it indicates that bituminous coal from Wanbei Ming Bureau(WB), anthracitic coalfrom Jiangxi Pingxiang(PX) and bituminous coal from Shanxi Datong(DT) all show the ashincreasing trends with the increasing particle size, while the ash of anthracitic coal samplesfrom Guizhou Liupanshui(LP) has a very small change and is nearly the same with the rawcoal samples. When one coal sample is grinding to different fineness, the changing trend ofthe size-ash curves is the same. Pulverized coals prepared by different type mill, the size-ashcurve changing with the coal samples. The grinding way has a large influence on the sizedistribution of mineral in pulverized coal.To research the influence of coal blending on mineral distribution of pulverized coalprepared by vibration mill, pulverized coal below15%fineness of the screen residue isprepared from the blended coal of the WB and DT, the WB and LP, the WB and YunnanXiaolongtan lignite (LT) with a5:5ratio. The results of industrial analysis on density fractionsof blended coal show that the preparation of different coal types leads to different yields withthe change of the densities. The ash content of each blended coals increases with the increaseof densities, while the volatile decreases. Average size of the pulverized coal in each densityfraction of blend coal of WB and DT, WB and LP decreases firstly and then increases.The research of effect of coal blending on the combustion characteristics shows that,with the same conditions of experiment and mixing proportion, the mixture of bituminouscoal and anthracite, the pre-grinding pulverized coal has a better combustion characteristicindex and comprehensive combustion performance than the pre-mixed pulverized coal exceptthe ignition characteristics. When bituminous coal is mixed with bituminous coal, the abovetwo mixing way have the approximate ignition characteristics and combustion characteristic.When bituminous coal is mixed with the lignite, the pre-mixed coal has a little bettercombustion performance than the coal mixed after grinding. The mixing way of bituminouscoal and anthracite has the most obvious influence on combustion. No matter which way tomix the coal, the bituminous coal mixed with the lignite has the best combustion reactionperformance followed by the bituminous coal mixed with bituminous coal, and thebituminous coal mixed with the anthracite coal has the worst performance. Combustion performance of the mixed coal that is grinded after mixed is greatly affected by the coal rank.The combustion characteristics of each size fraction of the bituminous coal andanthracite coal are studied by the thermogravimetry. The TG curve, ignition point, burning outtemperature, maximum weight loss rate and the corresponding temperature Tmax, conversionand conversion rate changing with temperature of different sieving granulation are analyzedand compared. With the same experimental conditions, the TG curve of the pulverizedbituminous move to the low temperature region when the sieved particle size decreases. Theignition point, burning embers performance, the combustion stability and the combustionreactivity of the pulverized coal and the overall combustion performance were improved. Inaddition, the smaller the size is, the more obvious the improvement is. Only the combustionTG curve of the pulverized coal of anthracite with small particle size moves to the lowtemperature region. The smaller the sieving granulation is, the better the ignition, thecombustion stability and the combustion reaction activity of pulverized coal are and the lowerthe temperature of burning embers is, but the degree of burn out is not always good when theparticle size is as small as possible. Bituminous coal has a greater influence of particle size onthe overall combustion performance of pulverized coal than the anthracite coal does.There are127figures,56tables and195literatures in the dissertation.
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